The Fox Illusion (フォックスイリュージョン Fokkusuiryūjon) is Fox's side special move. Performing the attack sends Fox darting forwards with ridiculous speed, which causes an afterimage effect and hurts any enemies in his path. The move first appeared in Super Smash Bros. Melee, and returns in Super Smash Bros. Brawl and Super Smash Bros. 4.
It deals little damage (3%) and has very little knockback, but can knock an enemy upward. The dash is so fast that if used facing an edge at the end of a stage, the attack will cause Fox to dart over the ledge, resulting in going into the helpless state, and usually causing a self-destruct.
The move may also be used by players as a useful recovery technique, since the move can quickly cover about half of the length of Final Destination and makes up for Fire Fox's easily being edge-guarded. However, unlike Fire Fox, Fox Illusion normally halts all momentum after a dash, which can sometimes give less recovery than Fire Fox.
Fox Illusion is an exclusive move to the Super Smash Bros. series, but it may have been inspired by the Arwing ability to boost itself, increasing it's speed for a small period of time.
 Special use
Fox Illusion (along with his semiclones' side specials, Falco Phantasm and Wolf Flash) can be cancelled with the special button. In each of these cancellations, the characters keep their horizontal momentum in the air. There are three points during the startup lag frames which the player can cause the dash to cancel in which these moves can be cancelled, but it is most easily done with Fox, due to his longer beginning lag. The first part for cancellation is right before he starts the dash. Fox will move just about 3 feet as if attempting to stop himself from dashing, stalling out if in midair. The second part is in mid-dash; canceling the attack now will send him slightly less than the normal Illusion distance, but his momentum will still carry him forward. The last part is right before the dash is completed and if the player attempts to cancel at this point, Fox will move slightly farther than the normal illusion distance due to leftover momentum. However, with practice, the player can control exactly when Fox will cancel. Since all three types of canceled Illusions can hurt the opponent, this is both useful to pseudo-wavedash while attacking (due to its sliding properties of landing on the ground), which can save him from punishment, as well as recovery, thanks to momentum leftover from the attack.